Summary: Yes, you can upgrade to a U845 with a faster CPU, but you'll still be getting a system that suffers from a cramped keyboard and a hotter-running chassis. The U845 just isn't as good a deal as it seems.
Conclusion: If Staples’ pricing happens to be a fluke, however, and the price hovers closer to Toshiba’s $879 MSRP, the U845-S406 becomes harder to recommend. Less-costly, lighter options like Sony’s VAIO T Series and Lenovo’s U310 are readily available.
Pros: Built-in WiDi for connecting to HDTVs, Backlit keyboard, More RAM than some competing machines
Cons: Design, features don’t stand out substantively from other ultrabooks, Test machine had hairline crack above SD-card slot